Clutch



K. MILLER Aug 5, 1941.

CLUTCH Filed Sept. 18, 1959 Patented Aug. 5, 1941 CLUTCH Kay Miller, Rockford, Ill., assignor to The Atwood Vacuum Machine Company., Rockford, Ill., a copartnership composed of Seth B. Atwood and James T. Atwood Application September 18, 1939, Serial No. 295,349

22 Claims.

'I his invention \r\elates to friction clutches and more particularly over-center type clutches especially designed for tractors but suitable, of course, for other heavy duty purposes. the present clutch being more specifically concerned with improvements in the type of clutch disclosed in the copending application of W. Vincent Thelander and myself, Serial No.v 194,337, filed March 7, 1938.`

The clutch disclosed in the earlier application embodies spring means between the pressure plate and over-center engaging means for the purpose of compensating in the spring means for wear on the clutch disk facings. The present clutch, however, embodies its spring means between the over-center engaging means and the back plate, this construction affording certain advantages both in the assembling of the clutch and in its operating characteristics, as will later appear.

The invention is illustrated in the accompanying drawing, in which- Figure 1 is a longitudinal section through a clutch made in accordanceA with my invention showing only so much as appears on one side of the longitudinal center line, whereby to permit showing the parts on a larger scale;

Fig. 2 is a sectional detail showing the method of assembling the two parts between which the spring means is caged in pre-loaded condition;

Fig. 2a is a perspective view of a disassembled group of parts which when assembled form one of the over-center clutch engaging levers employed;

Fig. 3 is a longitudinal section along the lines of Figure 1 showing modified or alternative construction, and

Fig. 4 is a sectional detail similar to Fig. 2 showing the method of assembling employed for a similar purpose in this design.

Similar reference numerals are applied to corresponding parts throughout the views.

Referring first to Figs. 1 and 2, the end portion of `the crank shaft of the engine is indicated in dotted lines at II and the flywheel at ment with the driving face I8 on the back ,of the` flywheel and the companion driving face I9 on the front of the pressure plate 20. The latter is suitably cast like the flywheel, and the faces I8 and I9 are accurately machined on these cast parts to insure smooth clutch engagement. The back plate 2l, in accordance with my invention, is stamped from sheet metal to the dished vform shown, so as to provide enough space between it and the pressure plate 20 for the bell-crank levers 22 which constitute the over-center engaging means of the clutch. The back plate is suitably secured to the rim of the flywheel by bolts entered through holes 23 in the flanged marginal portion 24 of the back plate. A pluv rality of equally circumferentially spaced lugs (not shown) cast integral with the pressure plate 20, project rearwardly therefrom, and these llugs have the side faces thereof machined smooth to slide freely on the sides of holes provided in the back plate, as shown in the earlier application.

In that way, the pressure plate turns with the ywheel, but is movable toward and away from the driving face I8 for engagement and disengagement 'of the clutch. Suitable spring means are also provided as disclosed in the earlier application tending normally to retract the pressure plate 20 toward the back plate 2I to insure immediate disengagement of the clutch when the levers 22 are Vmoved to the position shown in Figure 1 for disengagement of the clutch.

A plurality of stacked Belleville spring washer assemblies, indicated generally by the numeral 25, are held compressed between the back plate 2l and the levers 22 so as to provide a pre-loaded spring means for resiliently engaging the clutch, the term pre-loaded signifying that upon engagement of the clutch, said spring means are arranged to be subjected to further compressure,v and itis this increased spring pressure that is effective on 'the pressure plate 20 holding the clutch disk I5 engaged between the flywheel and pressure plate. The stacked spring washer assemblies 25, of which any suitable number are provided-eight are commonly used, are arranged all on the same radius and ln equally circumferentially lspaced relation. 26 is a sheet metal ring which has struck-up-cylindrical bosses 21 of a size to fit in the center holes 28 in one of the disks 29 and 30 of each of the assemblies 25 so as to locate the assemblies in the desired equally circumferentially spaced relation. The ring 26 has an inner circumferential iiange 3l tting around the inturned flange 32 on the back plate 2 I, whereby to hold the ring 26 in true concentric relation with the back plate. pressure plate and flywheel. 33 is an outer circumferential flange which is mainly for reinforcement of the ring 25, although it cooperates with the flange 3| to enclose or house the assemblies 25. 34 designates a sheet metal ring of channel-shaped cross-section whose web portion 35 has a series of holes 33 provided therein in equally clrcumferentially spaced relation at points preferably midway between the assemblies 25 to receive the shanks of rivets 31 that serve to fasten the rings 25 and 34 together. keeping the spring washer assemblies 25 in preloaded condition. 'lhe ring 25 has depressions 39 provided therein to receive the headed ends of the rivets 31 so that short shank rivets can be used to secure the ri'ngs together, washers 39 being provided on the reduced ends 40 of the rivets prior to the upsetting of the ends thereof as at 4|, to maintain the parts in permanently assembled relation. The pre-loaded spring pressure of the individual assemblies 25 will vary, of course, for different clutches, but as an example, I might state that the initial or preloaded spring pressure used in one clutch of the present design was about 160# per assembly, and in the engagement of the clutch, the spring washers 29 and 30 were arranged to be compressed further to an engagement pressure of about 245#. The amount of travel required in that clutch to change the compression from the pre-loaded pressure of 160# to the engagement pressure' of 245# was .060", and it follows, therefore, that a few thousandths of an inch wear on the clutch disk facings I1 under those conditions would not be noticeable and could notseriouslv affect the operation of the clutch, whereas in the ordinary unirnproved over-center clutch, a small amount of wear on the clutch disk facings resulted in excessive slippage and thereby accelerated the wear upon the facings and made necessary frequent accurate adjustments which only a specially skilled mechanic could make. In other words the spring means employed has a low rate characteristic within the operating range. Due to the amount of leeway afforded with the present spring compensated construction, substantially constant engaging pressure is obtained regardless of a normal amount of wear, and the clutch operates satisfactorily with fairly coarse adjustments. In passing, it will be seen that each assembly 25 has in combination with the two Belleville type spring washers 29 and 30, a spacer ring 42 held in centered relationship with the washers within the curled or flanged peripheries 43 thereof. The washers 29 and 30 are interchangeable. both having center holes 28. as indicated.

The levers 22 operate between the web portion 35 of the ring 34 and the inner rim portion 44 of the pressure plate 20. the levers being pivoted on fulcrum blocks 45 that are slotted lengthwise on one side as at 46 to straddle the projecting portion of arcuate cams 41 that are mounted in an annular groove 49 in the rim 44. The cams 41, of which there are four. one for each of four equally circumferentiallv spaced levers 22. are formed from strips stamped from sheet metal and subsequently formed to the desired arcuate form, as disclosed in the earlier application. The inclined surfaces 49 provided on each of the cams 41 provide the desired helical cam surface for the related fulcrum block 45, and when these fulcrum blocks are slid along the cams 41 by rotary adjustment of the levers 22 with the ring 34 in the manner described in the earlier application, there is a change in the relationship between the levers 22 and the spring means 25 and pressure plate 20 to compensate for wear on the clutch disk facings Il. The levers 22 work in slots 50 in the inner circumferential flange 5| of the ring 34 so as to turn with the ring 34 in the rotary adjustment thereof and slide the fulcrum blocks 45 along the cams 41. The outer circumferential flange 52 of the ring 54 has the edge portion thereof formed to provide teeth 59 between which a radial rib 54 on a leaf spring 55 secured to the back plate 2| is arranged to engage to hold the ring 34 in adjusted position. One or more holes 55 in the back plate 2| adjacent `the teeth 53 enable easy manual rotary adjustment of the ring 34. Obviously, as the ring 34 turns, the ring 26 is turned with it relative to the back plate 2|. Easy operation of the clutch is assured by rollers 51 which are annularly grooved as shown to receive the forked portion of the levers 22 and at the same time provide axles 59 to bear in said forks. These rollers operate on the flat inner face of the web portion 35 of the ring 34, and of course, move radially inwardly as the levers 22 are moved in a clockwise direction about their fulcrum blocks 45 by movement of the throwout collar 59 operated by the usual yoke or other clutchI operating means. l"I'he rollers 51' are moved slightly past dead center relationship to the fulcrum blocks 45 in the engagement of the clutch, the clutch deriving its name over-center type from this kind of operation. In the disengagement of the clutch the pressure plate 20 is retracted by spring action toward the back plate 2|, and the movement is limited by the engagement of the throwout collar 59 with a stamped sheet metal ring 60 that fits on the flange 32 of the back plate. Each of the levers 22 is connected with the throwout collar 59 by means of a pin 66 which has a cylindrical middle portion to fit a bearing.r hole in the end of the lever, but has flats provided on the end portions to fit slidably and non-rotatably in the slots 61 in the forked portion 68 on the throwout collar 59. The shape and mode of mounting the fulcrum blocks 45 and rollers 51 is thought to be clear from the showing in Fig. 2a.

'I'he clutch shown in Figs. 3 an-d 4 is similar in construction but has coiled springs 25a replacing the stacked spring washer assemblies. 25. the springs 25a being located in circumferentially spaced relation between the back plate 2|a and a ring 6|, and housed in stamped sheet metal cups 62 which fit in holes 63 provided in the back plate, and are held against displacement from the holes by annular outwardly projecting flanges 64. The springs 25a, of which there may be eight to correspond to the eight spring washer assemblies 25, an'd similarly spaced circumferentially with respect to the back plate 2|a. are pre-loaded and held under compression by the ring 6|, the latter being secured to the back plate 2|a by rivets 31a. These rivets fit in depressed portions 38a in the web portion 65 of the ring 6| and are entered through holes 66 in the back plate and receive washers 39a on the reduced ends thereof, which when upset as indicated at 4|a. keep rthe parts in permanently assembled relation. 'I'he ring 6| is channelshaped in cross-section and conformed to flt slldably on the ring 34a, which has the adiustment ring for the clutch similarly as the clutch 34 shown in Figure 1, this clutch being other- Wise Ysimilar. in construction to that rst described, as indicated by the-corresponding numbering of the remaining parts shown.

It is believed the foregoing description conveys a good understanding of the objects and advantages of my invention. The appended claims have been drawn to cover all legitimate modifications and adaptations.

I claim:

l. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a back plate for the ywheel, a pressure plate turning with the back plate and movable rtoward and away from the same in the disengagement and engagement of the clutch, respectively, positive-acting over-center means for moving the pressure plate away from the back plate to engage the clutch, Belleville spring washer means compressible between the back plate and overcenter means for resiliently transmitting pressure from the latter to the pressure plate. said Belleville spring washer means having an inherent low rate within its operating range. and means having lost-motion connection with the back plate holding the Belleville spring washer means in pre-loaded condition compressed to a point Within the low rate range but permitting further loading by said over-center mean when the latter is operated to engage the clutch and moves said holding means wi'thin its lost-motion connection.

2. In a friction clutch, the combination with a flywheel constituting the driving element, and

through the over-center means to the pressure' plate, a single ring for transmitting pressure from the over-center means to the spring means to engage the clutch resiliently, and another ring having lost motion connection with the first ring for holding the spring means in pre-loaded condition but permitting further loading by said over-center means when the latter is operated to engage the clutch and moves said holding Ameans within its lost-motion connection. A

3. In a friction clutch, the combination with a flywheel constituting the driving element, and

a clutch disc constituting the driven element, of

a back plate for 'the flywheel, a. pressure plate turning with the back plate and movable toward .A and away from the same in the disengagement and engagement of the clutch, respectively, a

plurality of springs carried on the back plate in circumferentially spaced relation, positive-acting over-center means for moving the pressure plate away from the back plate to engage the clutch,

. and a single intermediate member for transmitting pressure from the over-center means to the springs whereby to engage the clutch resiliently.

4. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a, back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from ithe same in the disengagement and engagement of they clutch, respectively, a

plurality oi' springs carried on the back plate in circumferentially spaced relation, positive-acting over-center means for moving the pressure plate away from the back plate to engage the clutch, a single intermediate member for transmitting pressure from the over-center means to the springs whereby to engage the clutch resiliently, and means for guiding said intermediate member for movement with respect to the back plate toward and away from the same, said meansv keeping the springs compressed to a predetermined initlal loading prior to the compression thereof upon operation of said over-center means.

5. In a friction clutch, the combination with a ywheel constituting the driving element, and a clutch disc constituting the drivenelement, of a back plate for the ywheel, a pressure plate turning Withthe back plate and movable toward and' away from the same in the disengagement vand engagement of the clutch, respectively, a

plurality of coiled compressionv springs carried on the back plate in cincumferentially spaced relation, positive-acting over-center means for moving the pressure plate away from the back plate to engage the clutch, a single intermediate member for transmitting pressure from the overcen'ter means to the springs whereby to engage the clutch resiliently, spring retainer cups mounted in holes provided in the back plate and housing said springs, and supports on the intermediate member slidable in holes in the back plate to guide the intermediate member relative to the back plate, said supports being further constructed to limit movement of said intermediate member away from the back plate so as to keep the springs pre-loaded.

6. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively. a plurality of springs carried on the back plate in cil cumferentially spaced relation, a ring member holding all of said springs in pre-loaded condition over-center means being relatively rotatably adjustable whereby to take up for wear in the engaging clutch faces.

'7. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch. respectively, a plurality of springs disposed in circumferentiallv spaced relation to the back plate. a pair of spaced ring members holding said springs therebetween in pre-loaded condition, said rings being movable relative to one another to permit further loading of said springs, positive-acting over-center means disposed between one of said rings and the pressure plate and arranged to move the .pressure plate away from the back plate and further loadsaid springs whereby to engage the clutch resiliently, and circumferentially extending cam means on the pressure plate providing a variable height abutment for the over-center means, said over-center means being rotatably adjustable relative to the cam means, whereby to take up for wear in the engaging clutch faces.

8. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting'the driven element, of a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively, a. plurality of springs disposed in circumferentially spaced relation toy the back plate, a pair of spaced ring members holding said springs therebetween in pre-loaded condition, said rings being movable relative to one another to permit further loading of said springs, positive-acting overcenter means disposed between one of said rings and the pressure plate and arranged to move the pressure plate away from the back plate and further load said springs whereby to engage the clutch resiliently, and circumferentially extending cam means on the pressure plate providing a variable height abutment for the over-center means, the aforesaid pair of rings being rotatably adjustable relative to the back plate and carrying the over-center means therewith so as to ad- :lust the same relative to the cam means Yto take up for wear in the engaging clutch faces.

9. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively, a plurality of Belleville spring washers disposed in circumferentially spaced relation relative to the back plate, a pair of spaced ring members holding the washers caged therebetween preventing more than a like predetermined axial expansion of all of the washers, and over-center means acting between one of said rings and the pressure plate. to force the pressure plate away from the back plate and engage the clutch resiliently under the combined pressure of said spring washers.

10. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a back plate for the ilywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively, a plurality of Belleville spring washers disposed in circumferentially spaced relation relative to the back plate, a .pair of spaced -ring members holding the washers caged therebetween preventing more than a like predetermined axial expansion` of all of the washers, over-center means acting between one of said rings and the pressure plate to force the pressure plate away from the back plate and engage the clutch resiliently under the combined pressure of said spring washers, and circumferentially extending cam means on the pressure plate providing a variable height abutment for the over-center means, said cam means and over-center means being relatively rotatably adjustable whereby to take up for wear in the engaging clutch faces.

11. In a friction clutch, the combination with a ilywheel constituting the driving element, and a clutch disc constituting the driven element, of a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same' in the disengagement and engagement of the clutch, respectively, a plurality of Belleville spring washer assemblies disposed in circumferentially spaced relation relativeto the back plate, each assembly comprising at least two opposed washers with a spacer therebetween allowing free travel of the movable edges of said washers, a pair of spaced ring members holding the assemblies in preloadedv condition caged therebetween preventing more than a like predetermined axial expansion of all of said washers, and over-center means acting between one of said rings and the pressure plate to move the latter away from the yback plate and engage the clutch resiliently under the combined pressure of said spring washer assemblies.

12. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc containing the driven element, of a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively, a ring mounted for rotary adjustment relative to the back plate, bell-crank levers rotatably adjustable with the ring relative to the back plate andmountled for pivotal movement between the back plate g and pressure plate to force the latter away from the back plate to engage the clutch, helical cam means on said pressure plate extending circumferentially with respect thereto and providing variable height surfaces thereon for abutment by said levers, and resilient means carried on the back plate and compressible by said ring to cause resilient engagement of the clutch.

13. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively, a ring mounted for rotary adjustment relative to the back plate, bell-crank levers mounted on said ring for pivotal movement between the back plate and pressure plate to force the latter away from the back plate to engage the clutch, helical cam means on said pressure plate extending circumferentially with respect thereto and providing variable height surfaces thereon for abutment by said levers, another ring having abutment with the back plate and mounted for rotary adjustment relative to the back plate with the ilrst ring, and resilient means compressible between said rings so as to cause resilient engagement of the clutch.

14. A clutch as set forth in claim 13, including means cooperating with the two rings to hold the resilient means under a predetermined preload, said means being so arranged with respect to the two rings as to permit further loading of said resilient means in the operation of the bellcrank levers to engage the clutch.

15. A friction clutch as set forth in claim 4, wherein the springs are of a type having an inherent low rate within the operating range.

16. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a back platefor the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively, a plurality of Belleville spring washers carried on the back plate in circumferentially spaced relation, positive acting over-center means for moving the pressure plate away from the back plate to engage the clutch, and a single intermediate member for transmitting pressure from the overcenter means to said Belleville spring washers, whereby to engage the clutch resiliently.

17. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively, a plurality of Belleville spring washers carried on the back plate in circumferentially spaced relation, positive acting over-center means for moving the pressure plate away from the back plate to engage the clutch, a single plate engaging said Belleville spring washers to transmit pressure from the over-center means to said Belleville spring washers to engage the clutch resiliently, said single plate being in substantially parallel spaced relation to the pressure platel and circumferentially extending cam means on one of the two last mentioned plates providing a variable height abutment for the over-center means. sai-d cam means and over-center means being relatively rotatably adjustable whereby to take up for wear in the engaging clutch faces.

18. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively, a plurality of Belleville spring washer assemblies disposed in circumferentially spaced relation relative to the back plate, each assembly comprising 'at least two opposed washers with a spacer therebetween allowing free travel of the movable edges of said washers, a plate holding the assemblies engaged between it and the back plate, preventing more than a like predetermined axial expansion of all the individual washers, over-center means for transmitting movement through said washer engaging plate to the washers in moving the pressure plate away from the back plate whereby to engage the clutch reslliently, the washer engaging plate being in substantially parallel spaced relation to the pressure plate, and circumferentially extending cam means on one of the two last mentioned plates providing a variable height abutment for the over-center means, said cam means and over-center means being relatively rotatably adjustable whereby to take up for wear in the engaging clutch faces.

19. In a friction clutch, the combination with a flywheel constituting the driving element,y and a clutch disc constituting the driven element, of.

a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively, a ring mounted for rotary adjustment relative to the back plate, bell-crank levers rotatably adjustable with the ring relative to the back plate and mounted for pivotal movement between the back plate and pressure plate to force the latter away from the back plate to engage the clutch, helical cam means on said pressure plate extending circumferentially with respect thereto and providing variable height surfaces thereon for abutment by said levers, another ring relative to vwhich the first ring is rotatable, and resilient means compressed between the back Aplate and the second ring and arranged to be subjected to further compression by the first ring in the engagement of the clutch.

20. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively, a ring mounted for rotary adjustment relative to the back plate. bell-crank levers rotatably adjustable with the ring relative to the back plate and mounted for pivotal movement between the back plate and pressure plate to force the latter away from the back plate to engage the clutch. helical cam means ongsaid pressure plate extending circumferentially with respect thereto and providing variable height surfaces thereon for abutment by said levers, another ring nonrotatable with respect to the back plate rotatably supporting the first ring, and resilient means compressible between the back plate and the second ring so as to cause resilient engagement of the clutch.

21. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively, a plurality of springs carried on the back plate in circumferentially spaced relation, positive-acting over-center means for moving the pressure plate away from the back plate to engage the clutch. cam means extending circumferentially with respect to the pressure plate for abutment by said over-center means, and a ring member for rotatably adjusting said over-center means relative to the cam means and transmitting pressure from the over-center means to the springs, whereby to engage the clutch resiliently.

22. In a friction clutch, the combination with a flywheel constituting the driving element, and a clutch disc constituting the driven element, of a back plate for the flywheel, a pressure plate turning with the back plate and movable toward and away from the same in the disengagement and engagement of the clutch, respectively, resilient means carried on the back plate in preloaded condition, positive-acting over-center means for moving the pressure plate away from the back plate to engage the clutch, cam means extending circumferentially with respect tothe pressure plate, and a ring member for rotatably adjusting said over-center means relative to the cam means and transmitting pressure from the over-center means to said resilient means to load the latter further so as to engage the clutch resiliently under increased pressure.

KAY MILLER..

, CERTIFICATE 'OF CORRECTION. Patent No. 2,251,567. August 5,19LL1.

KAY MILLER.

It is hereby certified that error appears in the printed specification ofl the above .mimbered patent requiring correction as follows: Page li, second column, line 19, claim 12, for the word "containin'gf' read `constituting; lines lill. andl|.5, claim 15, for "levers mounted .on said ring -rlead m-levers rotatably adjustable with the ring relative to Vthe backA plate and mounted; and that the said Letters Patent shouldbe read with this top r'fection therein thatthe same may conform to the record of the case in the PatentI Office.

sigma and sealed this 50th Yday of september, A. D. 191,1.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

